Undo in Vi and its successors
So vi only has one level of undo, which is simply no longer fit for the times we live in now, and also wholly unnecessary given even the least powerful devices that might need to run vi probably have more than enough resources to give at least a few more levels of undo. What I didn't know, however, is that vi's limited undo behaviour is actually part of POSIX, and for full compli
https://www.osnews.com/story/144459/undo-in-vi-and-its-successors/